Investigations into the flow of blood within the stomach have become more important in recent years because of attempts to define the relationship between mucosal blood flow and gastric acid secretion and because of attempts to define the etiology of superficial mucosal erosions (stress ulcers). Much controversy still remains regarding these matters. The proposed research is designed to provide new and quantitative information about the functional anatomy and physiology of the gastric microcirculation and the effects of physiologic and pathologic stimuli on their control mechanisms. Specifically, the aims of the proposal are: 1) To describe the living microvascular architecture of the stomach, particularly in the submucosal and mucosal layers, and to determine what differences exist between different functional regions of the stomach (antrum vs. body); 2) To determine the presence and functional significance of arteriovenous anastomoses (shunts) in these regions; 3) To determine the response of the gastric microcirculation to a low flow state (endotoxin shock); 4) To determine the gastric microcirculatory response to anticholinergic agents (atropine). And, 5) To determine the gastric microcirculatory response to surgical vagotomy. These studies will be performed on anesthetized rats and the microcirculation observed with a video-microscope system and recorded on a video tape recorder. Measurements will be made of vascular reactivity vessel dimensions, and blood flow under the experimental conditions described above. These direct in vivo observations will provide information that is not possible to obtain using other methods of studying gastric blood flow.